CANDIDATE: Dr. Sepulveda has an MD from the University of Lisbon and a PhD in Cell Biology from Baylor College of Medicine. He completed residency in Clinical Pathology and fellowship in Transfusion Medicine at Baylor, and served full time since 1999 as Assistant Chief of Laboratory at the Houston VAMC. In 8/2000 he joined the Department of Pathology at the University of Pittsburgh, wherein 80 percent of his time is protected for research. Dr. Sepulveda goals are to develop a comprehensive research program to effectively dissect the pathways leading to heart failure (HF) and to explore mechanistic interventions aimed at modulating cardiomyocyte phenotypes and improving the natural history of heart failure. Dr. Sepulveda has start up funds, adequate laboratory space and access to the resources of Pathology, Cardiology, and core facilities at the University of Pittsburgh. BACKGROUND: Patients with HF have a 5-year survival rate of less than 50 percent. During progression of HF, cardiomyocytes undergo neuroendocrine stimulation. Different stimuli result in different hypertrophy phenotypes with expression of different isoforms of cardiac proteins. Hypertrophy temporarily results in increased contractility but ultimately cardiomyocyte remodeling, elongation and contractile failure occur. HYPOTHESIS: I. During hypertrophic stimulation, changes in the combinatorial activity of transcription factors SRF, GATA4 and Nkx2-5 leads to modulation of transcription of various isoforms of cardiac-specific genes. II. In decompensated HF, down-regulation of SRF, GATA4 and Nkx2-5 results in insufficient transcription of contractile proteins and consequent inotropic failure. AIM 1: To test the hypothesis that changes in levels of SRF, GATA4 and Nkx2-5 occur during HF progression, by measuring mRNA and protein levels in cardiomyocytes stimulated with hypertrophic agents, and in heart extracts from tumor necrosis factor-alpha transgenic mice (a model of HF). AIM 2: To test the hypothesis that functional changes in SRF, GATA4 and Nkx2-5 occur during hypertrophic stimulation and HF progression. Function will be characterized by measuring DNA binding affinity, transcriptional activation and interactive proteins. AIM 3: We will inactivate SRF, GATA4 and Nkx2-5 to test the hypothesis that these factors are critical for regulating transcriptional switches during hypertrophic stimulation of cardiomyocytes. We will measure the changes in hypertrophic phenotype and specific target genes in cardiomyocytes stimulated with hypertrophic agents. IMPACT: These studies are essential to understand the molecular mechanisms that underlie cardiomyocyte phenotype changes in HF progression and will have a general impact on clarifying transcriptional regulatory pathways in cardiomyocytes. These advances in the understanding of the mechanisms of HF may suggest diagnostic, therapeutic and preventive strategies to help modify the currently dismal prognosis of heart failure.